BUG: work around NumPy 1.6.1 datetime64 bug, close #1561

RELEASE.rst

@@ -61,6 +61,7 @@ pandas 0.8.1
   - Selection of multiple SparseDataFrame columns by list in __getitem__ (#1585)
   - Override Index.tolist for compatibility with MultiIndex (#1576)
   - Fix hierarchical summing bug with MultiIndex of length 1 (#1568)
+  - Work around numpy.concatenate use/bug in Series.set_value (#1561)
 
 pandas 0.8.0
 ============

pandas/core/series.py

@@ -742,7 +742,11 @@ def set_value(self, label, value):
             self.index._engine.set_value(self, label, value)
             return self
         except KeyError:
-            new_index = np.concatenate([self.index.values, [label]])
+            if len(self.index) == 0:
+                new_index = Index([label])
+            else:
+                new_index = self.index.insert(len(self), label)
+
             new_values = np.concatenate([self.values, [value]])
             return Series(new_values, index=new_index, name=self.name)
 

pandas/tseries/tests/test_timeseries.py

@@ -1691,8 +1691,22 @@ def test_datetimeindex_union_join_empty(self):
         result = dti.join(empty)
         self.assert_(isinstance(result, DatetimeIndex))
 
-    # TODO: test merge & concat with datetime64 block
+    def test_series_set_value(self):
+        # #1561
 
+        dates = [datetime(2001, 1, 1), datetime(2001, 1, 2)]
+        index = DatetimeIndex(dates)
+
+        s = Series().set_value(dates[0], 1.)
+        s2 = s.set_value(dates[1], np.nan)
+
+        exp = Series([1., np.nan], index=index)
+
+        assert_series_equal(s2, exp)
+
+        # s = Series(index[:1], index[:1])
+        # s2 = s.set_value(dates[1], index[1])
+        # self.assert_(s2.values.dtype == 'M8[ns]')
 
 class TestSeriesDatetime64(unittest.TestCase):